pg_visibility: Use visibilitymap_count instead of loop.

This commit updates pg_visibility_map_summary() to use the
visibilitymap_count() API, replacing its own counting mechanism. This
simplifies the function and improves performance by leveraging the
vectorized implementation introduced in commit 41c51f0c68.

Author: Matthias van de Meent <boekewurm+postgres@gmail.com>
Reviewed-by: wenhui qiu <qiuwenhuifx@gmail.com>
Reviewed-by: Masahiko Sawada <sawada.mshk@gmail.com>
Discussion: https://postgr.es/m/CAEze2WgPu-EYYuYQimy=AHQHGa7w8EvLVve5DM5eGMR6zh-7sw@mail.gmail.com

diff --git a/contrib/pg_visibility/pg_visibility.c b/contrib/pg_visibility/pg_visibility.c
index 7046c1b5f8e54a7b32c487702f6ea98820ad35ca..715f5cdd17c5773ed0dad88e11b286b039f65b0e 100644 (file)
--- a/contrib/pg_visibility/pg_visibility.c
+++ b/contrib/pg_visibility/pg_visibility.c
@@ -270,11 +270,8 @@ pg_visibility_map_summary(PG_FUNCTION_ARGS)
 {
        Oid                     relid = PG_GETARG_OID(0);
        Relation        rel;
-       BlockNumber nblocks;
-       BlockNumber blkno;
-       Buffer          vmbuffer = InvalidBuffer;
-       int64           all_visible = 0;
-       int64           all_frozen = 0;
+       BlockNumber all_visible = 0;
+       BlockNumber all_frozen = 0;
        TupleDesc       tupdesc;
        Datum           values[2];
        bool            nulls[2] = {0};
@@ -284,33 +281,15 @@ pg_visibility_map_summary(PG_FUNCTION_ARGS)
        /* Only some relkinds have a visibility map */
        check_relation_relkind(rel);
 
-       nblocks = RelationGetNumberOfBlocks(rel);
-
-       for (blkno = 0; blkno < nblocks; ++blkno)
-       {
-               int32           mapbits;
-
-               /* Make sure we are interruptible. */
-               CHECK_FOR_INTERRUPTS();
-
-               /* Get map info. */
-               mapbits = (int32) visibilitymap_get_status(rel, blkno, &vmbuffer);
-               if ((mapbits & VISIBILITYMAP_ALL_VISIBLE) != 0)
-                       ++all_visible;
-               if ((mapbits & VISIBILITYMAP_ALL_FROZEN) != 0)
-                       ++all_frozen;
-       }
+       visibilitymap_count(rel, &all_visible, &all_frozen);
 
-       /* Clean up. */
-       if (vmbuffer != InvalidBuffer)
-               ReleaseBuffer(vmbuffer);
        relation_close(rel, AccessShareLock);
 
        if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
                elog(ERROR, "return type must be a row type");
 
-       values[0] = Int64GetDatum(all_visible);
-       values[1] = Int64GetDatum(all_frozen);
+       values[0] = Int64GetDatum((int64) all_visible);
+       values[1] = Int64GetDatum((int64) all_frozen);
 
        PG_RETURN_DATUM(HeapTupleGetDatum(heap_form_tuple(tupdesc, values, nulls)));
 }